A suspension thrust bearing device is usually provided with a rolling bearing comprising a top ring and a bottom ring between which are positioned rolling elements, for example balls or rollers, and with bottom and top bearing or support pieces, such as covers or cups. The top and bottom covers form a housing for the rings of the rolling bearing and provide the interface between said rings and the neighboring elements.
A suspension thrust bearing device is positioned in the top part of the suspension strut between the bodywork of the vehicle and a suspension spring. The spring is fitted around a damping piston rod, the end of which is linked to the bodywork of the vehicle through an elastic block that filters the vibrations. The suspension spring axially bears, directly or indirectly, on the bottom cover. The top cover is fixed relative to the bodywork of the vehicle.
The rolling bearing makes it possible to transmit axial forces between the suspension spring and the bodywork of the vehicle, while allowing a rotation movement between the bottom cover and the filtering elastic block. This relative angular movement derives from a steer angle of the steered road wheels of the vehicle and/or the compression of the suspension spring.
The French patent application FR-A1-2 918 138 discloses such a suspension thrust bearing device comprising a bottom support cover, a top bearing cover and a rolling bearing axially disposed between said covers. To limit the intrusion of water, dust and other foreign matter between said covers, the device further comprises sealing rings mounted into radial grooves of the bottom support cover and coming into friction contact with external and internal skirts of the top bearing cover.
With such a device, if the bottom support cover is deformed under the effect of the axial loads of the suspension spring, an axial gap may occur between the top bearing cover and one of the sealing rings.
The European patent application EP-A1-1 870 265 also discloses a suspension thrust bearing device comprising a bottom support cover, a top bearing cover, a rolling bearing and sealing rings axially disposed between said covers. The sealing rings are moveable both axially and radially between the covers.
In this document, due to the design of the seals and to their disposition relative to the bottom and top covers, the sealing obtained between said covers may be insufficient in some operating conditions and foreign matter may reach the rolling bearing.
One aim of the present invention is therefore to overcome the aforementioned drawbacks.
It is a particular object of the present invention to provide an axial thrust bearing device which is simple to manufacture and to assembly, economic, while guaranteeing good sealing properties.